The present invention relates to picture frame assemblies and particularly to a corner bracket used in the assembly of the picture frames of the type generally referred to as "art frames", i.e., formed of extruded aluminum and/or plastic channel members.
Ordinarily such frames are formed of extruded border members, having a channel open to the front face for the receipt of a picture or other art subject, glass, matting, etc. in conventional arrangement, and at least one channel on the rear face permitting the introduction of corner brackets, by which the border members are assembled and held together. In addition hanging brackets and the like are insertable into channels so that the frame may be hung or otherwise manipulated.
The known assemblies have a number of problems and difficulties attendant to the construction and use of the corner brackets. Generally, a metal angle bracket is employed having flat, blade-like arms which are inserted longitudinally into the corresponding channels in the adjacent border members. The inserts of the brackets are then held in place by screw means passing through the faces of the brackets to be pressed securely against the border members, thus holding the corner brackets in place and securing the border members from relative movement with respect to each other as well as relative to the corner brackets.
It was also known to provide an angle bracket with flexible projections extending from one face so that the projections and brackets can be transversely insertable into the rear channel, by merely pressing it therein. Such members generally made of rubber or relatively soft plastic did not hold well and the border members could be easily pulled apart. Where such elastic angle brackets were made of harder material, they were more difficult to insert into the rear grooves of the border members and required the use of tools to do so. The difficulty of this type arrangement was overcome in the construction shown in applicant's patent U.S. Pat. No. 4,428,135, in which the bracket was provided with a pair of spaced parallel ribs on its rear side each having an outwardly extending flange which after insertion into the channel engage the inner surface of the rear wall. A problem arising from this construction lay in the fact that the angle bracket itself lay flat against the exterior surface of the rear wall of the border member which thus caused the frame to stand somewhat away from the wall on which it was placed by the thickness of the bracket.
Another form of angle corner bracket is shown in Kapnek, U.S. Pat. No. 4,205,470 wherein the corner bracket is formed of flat metal and is bifurcated at each of the free ends of its legs into a pair of fingers. The outer corners of each finger terminate in a point or in a cutting edge extending outwardly opposite to each other transverse to the direction of the leg. This corner bracket is inserted into the slot of a border member, which is made of material which is substantially softer, i.e. wood or plastic, than the metal corner bracket. After such insertion, a blade member or cam is inserted between each of the pairs of legs and twisted by the use of a suitable tool, such as a plier so as to force the lower extremities of each pair of fingers outward, consequently causing the points or cutting edges to bite and dig into the walls of the rear slot.
While this construction is somewhat simpler than previously known, it has the disadvantage that the corner bracket, particularly the points or protuberances thereof, must be particularly fashioned since they must have effectively shaped points to bite into the border member. Further, the border member must be made of a material which is softer than the corner bracket or conversely, the corner bracket must always be made of a relatively hard material such as iron or steel. Another disadvantage lies in the fact that the retaining blade member or cam is merely twisted into place and therefore subject to becoming loose. As a result, it frequently dislodges from its effective position, afterwhich the border members can be easily pulled apart.
It is an object of the present invention to provide a corner bracket member for frame assemblies of the type described in which disadvantages and difficulties enumerated above are overcome and/or avoided.
It is a specific object of the present invention to provide a frame assembly having channeled border members joined by an easily constructed, and simply usable corner bracket, which can be assembled without the use of any special tools whatsoever.
It is a further object of the present invention to provide a corner bracket which can be assembled with a channeled border member without having any destructive effect on the channeled border member, yet being firm and secure over the life of the use of the assembly.
The foregoing objects, together with other objects, features, and advantages of the present invention will become apparent in the following disclosure.